The present invention relates generally to improved methods, parts, and systems for reducing noise and vibration characteristics in an automotive vehicle. More particularly, the invention relates to an anti-vibration damping device or system integrated along at least a portion of an automotive body panel assembly resulting in the reduction of vibration, the improvement of sound absorption characteristics, and enhancement of appearance of the exterior portion of outer body panels of automotive vehicles.
Traditional automotive vehicle assembly operations generally require a number of specific pre-assembly manufacturing steps or processes, which occur prior to final assembly of the vehicle. Typically, one step or process involves the application of chemical compositions to the unseen or interior portions of an automotive body panel assembly in an effort to reduce vibration and movement of the automotive body panel once it is integrated within the vehicle by the manufacturer. This process typically requires the vehicle manufacturer to allocate tooling and manufacturing facilities for the application of such chemical compositions at either a separate stamping facility where the body panel is assembled or in the vehicle assembly plant during final production. One such technique employs the use of pumpable products applied to the body panel in the form of xe2x80x9cwetxe2x80x9d compositions, which can remain tacky or may otherwise be applied to the selected panel in a non-uniform manner. For instance, one popular technique utilizes a pumpable product consisting of a thermally activated polymeric material which upon heat activation expands and fills a space or cavity defined between the inner and outer portions of the chosen panel of an automotive vehicle. Another technique found in the prior art utilizes the application of a pressure sensitive patch to an inner portion of an outer body panel.
While these prior art devices perform well and are advantageous in many circumstances, they often require a large capital investment to integrate the pumpable product into the chosen manufacturing facility, utilize a large amount of floor space and maintenance clean-up resources at the stamping facility or final vehicle assembly plant, and require an additional manufacturing process and labor demand. In turn, the manufacturer is required to devote both financial and technical resources to develop tooling for delivering the pumpable product as well as transportation costs, which adds potential cost and delay, particularly if changes to the vehicle structure are implemented during the design stages.
The pressure sensitive patch system also requires an additional manufacturing step, tooling costs, and attendant labor demand at the stamping facility or vehicle assembly plant to insert the patch to the chosen body panel. Further, the aesthetic qualities and overall appearance of the exterior portion of outer body panels of the vehicle is potentially reduced or diminished when utilizing the patch system due to differences in the thermal expansion and cycling characteristics of the patch material and the exterior portion of the outer body panel. In this regard, exposure to the heat typically encountered in a conventional automotive paint operation serves to thermally expand both the patch material and the outer body panel so that the patch material expands into contact with the outer body panel to absorb the vibrational energy. However, differences in thermal characteristics between the materials may cause an outline or profile of the patch to be visible or read through the exterior portion of the outer body panel of the vehicle due to thermal contraction of the panel against the expanded and cured patch material.
Accordingly, there is need for a simple low cost system that provides an integrated anti-vibration damping material within an automotive body panel assembly to reduce vibration characteristics and which can be employed across a wide range of different sizes or shapes of body panel configurations and applications found in automotive vehicles.
The present invention is directed to a damping or vibration reduction system, and particularly one for automotive vehicle frame structures, such as (without limitation) body panel assemblies of automotive vehicles. In a particularly illustrative and non-limiting embodiment, the system of the present invention is utilized in body panels found in an automotive door assembly for the damping or reduction in vibration of the outer door panel as it is opened and closed. The system generally employs at least one damping member, which is attached or adhered to at least one portion of the panel assembly such as the inner body panel, an interior or inner portion of the outer body panel, or an intrusion beam disposed between the inner and outer body panels of the selected body panel assembly. The damping member or plurality of members can be configured or shaped in any selected form, design, or shape corresponding to the chosen space or panel requiring vibrational damping. The member has at least one exterior edge or surface suitable for receiving an application of an expandable material. It is contemplated that the expandable material disclosed in the present invention functions as an anti-vibration damper when expanded and bonded in a radial direction from the damping member to an inner or interior portion of an outer body panel when the panel assembly is processed through electrocoating, and paint cycles in a vehicle assembly plant. After expansion and curing, the expandable material disposed along the damping member remains in fixed contact with the outer body panel of the automotive vehicle thereby absorbing and transferring vibrational energy from the outer body panel and reducing vibrational movement.
In the illustrative embodiment of the automotive door assembly, at least one damping member having anti-vibration expandable material disposed along at least a portion of the damping member is snap-fit mounted or otherwise attached to an intrusion beam having a first end and a second end disposed and mounted between an inner door panel and an outer door panel of an automotive door assembly fixedly bridging the assembly. The expandable material disposed on the exterior edge or surface of the damping member expands and bonds the intrusion beam with either or both of the inner and outer door panels when the intrusion beam (now attached to the vehicle in the final assembly operation) is processed through e-coat and paint operation cycles in a vehicle assembly plant.
In one embodiment, the material is heat expandable and at least partially fills the cavity by structurally bonding the intrusion beam and the outer door panel, and possibly the inner door panel depending upon the size and shape of the door cavity, during the painting operation thereby reducing noise and vibration characteristics of the vehicle as well as producing a more quite door assembly when the vehicle door is opened and closed. In another embodiment, the material is a melt-flow material, and upon the application of heat will spread over a surface. The selected expandable material can provide a variety of characteristics including structural reinforcement, acoustical damping, vibrational reduction, or any combination thereof.
The present invention further serves to eliminate handling or disposal issues often encountered in the use of a pumpable product process or application of xe2x80x9cwetxe2x80x9d chemical technology in either a pre-assembly stamping facility or a vehicle assembly plant. The anti-vibration expandable material can be extruded or mini-application bonded onto the damping member in either a pre-production setting or the final vehicle assembly operation. The damping member, with the expandable material disposed along the edges or surface of the member, is then attached or adhered to the selected body panel assembly prior to the e-coat or paint operation processing. Hence, the present invention can be utilized by either the body panel manufacturer or the vehicle manufacturer during final assembly with reduced labor, maintenance requirements, and floor space demand. In addition, upon activation in the e-coat or paint operation process, the expandable material placed along the damping member provides seamless reinforcement and vibrational reduction of the outer body panel, which does not affect the exterior visual appearance of the automotive vehicle.